True Color - Corrected Reflectance (MODIS / Terra)

Overview and Intended Use This visualization represents a "true color" band combination (Red = 1, Green = 4, Blue = 3) of data collected by the MODIS instrument on the NASA Terra satellite. The imagery is most similar to how we see the Earth’s surface with our own eyes. It is a natural looking image that is useful at a global and regional scale. At its highest resolution, this visualization represents the underlying data scaled to a resolution of 250m per pixel at the equator. The MODIS Corrected Reflectance product provides natural-looking images by removing gross atmospheric effects such as Rayleigh scattering from the visible bands. By contrast, the MODIS Surface Reflectance product, which is also available in the Living Atlas, provides a more complete atmospheric correction algorithm that includes aerosol correction and is designed to derive land surface properties. In clear atmospheric conditions the Corrected Reflectance product is similar to the Surface Reflectance product, but they depart from each other in the presence of aerosols. Multi-Spectral Bands The following table lists the MODIS bands that are utilized to create this visualization. See here for a full description of all MODIS bands. Band Description Wavelength (µm) Resolution (m) 1 Visible (Red) 0.620 - 0.670 250 3 Visible (Blue) 0.459 - 0.479 500 4 Visible (Green) 0.545 - 0.565 500 Temporal Coverage and Limitations of Use By default, this layer will display the imagery currently available for today’s date. The update frequency of the imagery is a "daily composite" that is assembled from hundreds of individual data files. When viewing imagery for “today,” you may notice that only a portion of the map has imagery. This is because the visualization is continually updated as the satellite collects more data. To view imagery over time, you can update the layer properties to enable time animation and configure time settings. The current version of this layer is available from present back to the start of the mission (February 24th, 2000). Source: NASA Global Imagery Browse Services (GIBS), NASA Worldview, & NASA LANCE This visualization is provided through the NASA Global Imagery Browse Services (GIBS), which are a set of standard services to deliver global, full-resolution satellite imagery for hundreds of NASA Earth science datasets and science parameters. Through its services, and the NASA Worldview client, GIBS enables interactive exploration of NASA's Earth imagery for a broad range of users. The data and imagery are generated within 3 hours of acquisition through the NASA LANCE capability. Esri and NASA Collaborative Services This visualization is made available through an ArcGIS image service hosted on Esri servers and facilitates access to a NASA GIBS service endpoint. For each image service request, the Esri server issues multiple requests to the GIBS service, processes and assembles the responses, and returns a proper mosaic image to the user. Processing occurs on-the-fly for each and every request to ensure that any update to the GIBS imagery is immediately available to the user. As such, availability of this visualization is dependent on both the Esri and the NASA GIBS services.概述与预期用途 此可视化成果展示了NASA Terra卫星上搭载的中分辨率成像光谱仪（MODIS）所采集数据的“真彩色”波段组合（红=波段1，绿=波段4，蓝=波段3）。该影像与人类肉眼所见的地球表面景观高度相似，是一张符合自然视觉效果的图像，适用于全球及区域尺度的分析。在最高分辨率下，此可视化成果的原始数据在赤道处的像素分辨率被缩放至250米。 MODIS校正反射率产品（MODIS Corrected Reflectance product）可通过移除可见光波段的瑞利散射等显著大气效应，生成符合自然视觉效果的影像。相比之下，同期可在Esri Living Atlas中获取的MODIS地表反射率产品（MODIS Surface Reflectance product）则采用了更完善的大气校正算法，包含气溶胶校正，旨在反演陆地地表属性。在大气清澈的条件下，校正反射率产品与地表反射率产品的结果相近，但在存在气溶胶时，二者的输出结果会出现差异。 多光谱波段 下表列出了用于生成此可视化成果的MODIS波段。完整的MODIS波段说明请参见此处。 | 波段 | 波段描述 | 波长（μm） | 分辨率（米） | |------|----------|-----------|------------| | 1 | 可见光（红光） | 0.620 - 0.670 | 250 | | 3 | 可见光（蓝光） | 0.459 - 0.479 | 500 | | 4 | 可见光（绿光） | 0.545 - 0.565 | 500 | 时间覆盖范围与使用限制 默认情况下，此图层将显示当前最新的当日日期影像。影像更新频率为“每日合成”，由数百份独立数据文件拼接而成。当查看“今日”影像时，您可能会发现地图仅部分区域覆盖有影像，这是因为该可视化成果会随着卫星采集到更多数据而持续更新。若需查看随时间变化的影像，您可以修改图层属性以启用时间动画并配置时间设置。当前版本的该图层可获取的影像范围为自任务启动之日（2000年2月24日）起至今的所有数据。 数据来源：NASA全球影像浏览服务（GIBS, NASA Global Imagery Browse Services）、NASA Worldview及NASA LANCE 本可视化成果由NASA全球影像浏览服务（GIBS）提供，该服务是一套标准化的服务体系，可面向数百项NASA地球科学数据集与科学参数提供全球全分辨率卫星影像。依托其服务与NASA Worldview客户端，GIBS可支持广大用户交互式探索NASA地球影像资源。通过NASA LANCE系统，采集到的卫星数据与影像可在3小时内完成生成并对外提供。 Esri与NASA合作服务 此可视化成果通过托管于Esri服务器的ArcGIS影像服务发布，可便捷访问NASA GIBS服务端点。每一次影像服务请求都会由Esri服务器向GIBS服务发起多条子请求，对返回结果进行处理与拼接后，向用户返回完整的镶嵌影像。所有请求均会实时处理，以确保GIBS影像的任何更新均可立即对用户开放。因此，本可视化成果的可用性同时依赖于Esri服务与NASA GIBS服务。